Heretofore chain saw sharpening devices have been provided whereby both the right and left hand teeth of a saw chain may be sharpened. However, in order to sharpen a chain in a manner such that it may cut in a perfectly even manner, precisely the same bevel and depth of bevel must be formed not only on each cutting tooth on one side of the chain, but the same bevel and depth of bevel must be formed on the cutting teeth on the other side of the chain. The chain saw sharpener and automatic chain sharpener disclosed in my above-mentioned copending application and patent are capable of performing this function and there have been other prior patented chain saw sharpeners which are purported to be capable of also performing this function.
However, these previously designed machines for sharpening saw chains in a manner such that the teeth on opposite sides of the chain will all be sharpened to substantially the same configuration require that the chain to be sharpened be supported on a first support for sharpening the teeth on one side of the chain and then removed for support on a second support for sharpening the teeth on the other side of the chain. This necessary step of transferring the saw chain from one support to a second support in order to sharpen the teeth on both sides of the chain is not only an extra step required in the process of sharpening a saw chain but also raises the opportunity of error in the proper placement of the two chain supports in relation to the rotary grinding head and thus the possibility of the teeth on opposite sides of the chain not being uniformly sharpened unless a proper positioning of the two saw chain supports in relation to the rotary grinding head is checked frequently. Further, the necessity of providing two saw chain supports results in unnecessary duplication of parts and higher cost of manufacture.
Examples of previously patented saw chain sharpening machines including some feature which are similar to various components of the instant invention may be found in U.S. Pat. Nos. 2,217,145, 2,318,456, 2,353,956, 2,410,828, 3,592,085, 3,611,839 and 3,779,103.